JP2001244609A - Method of manufacturing wiring board and wiring board obtained with the same method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of easily manufacturing a wiring board, with reduction in cost, that can cover the scale-down of wire for high integration density and application into a highly reliable multilayer wiring board and also provide a wiring board obtained with the same method. SOLUTION: With the injection molding of resin, a base material 11 having a groove 12 for wiring at one main surface thereof is obtained. A through-hole 13 provided through the base material 11 is formed to the groove 12 of the through-hole forming area with a laser beam or a drill. Next, the groove 12 and hole 13 of the base material 11 are filled with a conductive paste 14 as the conductive material. Thereafter, the conductive paste 14 is dried up under the predetermined temperature for the purpose of hardening. Finally, a contamination layer (remaining conductive paste) on the surface is removed with the surface fine polishing of the main surface of the wiring side. Thereby, a single- sided board 1 can be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a wiring board used in a surface mounting process and a wiring board obtained by the method.

[0002]

2. Description of the Related Art In a conventional method of manufacturing a wiring board using a conductive paste, a conductive paste is used for a via portion connecting between layers, but a pattern is formed by etching a conventional copper foil. I have. Therefore, the step of forming a via portion between layers with a conductive paste and the step of etching and forming a pattern are separate, which is disadvantageous in terms of manufacturing cost and manufacturing lead time.

[0003] Further, since the copper foil is etched, it is difficult to make the wire thinner, and there is a large variation in finishing accuracy. These are disadvantageous in terms of high integration, high speed and high frequency in the future. Also, when laminating the wiring boards, the connection between each layer is taken with the structure of bonding the conductive paste and the copper foil,
Adhesive strength is weak and there is concern about reliability.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above point, and can be applied to a highly reliable multi-layer substrate which can cope with thinning for high integration. It is an object of the present invention to provide a method of manufacturing a wiring board that can easily obtain a wiring board with a reduced manufacturing cost, and a wiring board obtained by the method.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a method of manufacturing a wiring board by supplying a substrate material to a mold having a cavity having a predetermined shape and molding the same. A step of forming a cavity on the one main surface side by mounting a transfer mold in which a convex pattern to be transferred to a material is formed and a mold body; and supplying a substrate material to the cavity and forming a wiring groove. And a step of forming a wiring by filling the wiring groove with a conductive material to provide a wiring board manufacturing method.

According to this method, since a groove for a wiring pattern can be formed during molding, an etching step is not required. Thus, simplification of the processing steps can be realized, and processing time and processing cost can be reduced.

In the method of manufacturing a wiring board according to the present invention,
A step of forming a through hole in the base material, wherein when the conductive material is filled in the wiring groove, the wiring is also filled in the through hole and the wiring on both surfaces of the base material is made conductive with the conductive material. Is preferred.

According to this method, the formation of the wiring and the formation of the through-hole can be performed collectively by filling the conductive material.

In the method for manufacturing a wiring board according to the present invention,
It is preferable that the method further includes a step of grinding and polishing the main surface of the base material after filling the wiring groove with a conductive material. Thereby, the conductive material remaining on the surface of the base material can be removed.

In the method for manufacturing a wiring board according to the present invention,
The step of grinding and polishing the main surface of the base material is a process of flattening one main surface of the base material and then flattening the other main surface of the base material using the one main surface as a reference surface. It is preferable to include

According to this method, it is possible to suppress the variation in the thickness of the wiring and the variation in the wiring impedance. Thereby, the characteristics in the high frequency region are improved.

In the method for manufacturing a wiring board according to the present invention,
It is preferable that the one main surface is a surface having no wiring and the other main surface is a surface having wiring. This makes it possible to more accurately suppress variations in the thickness of the wiring.

According to the present invention, a cavity is formed on the one main surface side by mounting a transfer mold having a convex pattern to be transferred to a wiring board formed on one main surface to a mold body. And forming a substrate by supplying a substrate material to the cavity to form a base material having a wiring groove, and forming a wiring by filling the wiring groove with a conductive material. Provide a substrate.

According to this configuration, it is possible to cope with thinning for high integration, and to apply it to a highly reliable multilayer substrate.

[0015]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. 1 to 3
FIG. 4 is a process diagram for describing a method for manufacturing a wiring board according to one embodiment of the present invention.

First, a process for manufacturing a single-sided substrate will be described with reference to FIG. As shown in FIG. 1A, a base material 11 having a wiring groove 12 on one main surface is obtained by injection molding of a resin. Then, as shown in FIG. 1B, the grooves 12 in the through-hole forming portions are formed by a laser or a drill.
A hole 13 that penetrates the base material 11 is formed.

Next, as shown in FIG.
A conductive paste 1 which is a conductive material in the grooves 12 and the holes 13
Fill 4 Thereafter, the conductive paste 14 is dried at a predetermined temperature and cured. Finally, as shown in FIG. 1D, the main surface on the wiring side is precisely polished to remove the contamination layer (remaining conductive paste) on the surface. Thus, the single-sided substrate 1 is manufactured.

The resin used for injection molding is, for example, LCP, PEEK, PEI, PSF, SP
A thermoplastic resin (super engineering plastic) having high heat resistance and high strength such as S and PES can be used. In addition,
Injection molding conditions are determined according to the characteristics of each resin.
Further, the base material 11 may be formed by forming a groove by press working on a base material made of a thermosetting resin instead of injection molding. Alternatively, the base material 11 may be configured by preparing a thermoplastic resin sheet and performing a hot press process or a thermal transfer roll process on the sheet.

Next, the manufacturing process of the double-sided substrate will be described with reference to FIG. As shown in FIG. 2A, a base material 11 having wiring grooves 12 on both main surfaces is obtained by resin injection molding. Then, as shown in FIG. 2 (b), the grooves 12 in the through-hole forming portions are formed by a laser or a drill.
A hole 13 that penetrates the base material 11 is formed.

Next, as shown in FIG.
A conductive paste 1 which is a conductive material in the grooves 12 and the holes 13
Fill 4 Thereafter, the conductive paste 14 is dried at a predetermined temperature and cured. Finally, as shown in FIG. 2D, the main surface on the wiring side is precisely polished to remove the contamination layer (remaining conductive paste) on the surface. Thus, the double-sided substrate 2 is manufactured.

Next, as shown in FIG. 3 (a), the single-sided substrate 1 and the double-sided substrate 2 manufactured as described above are laminated and pressed at a predetermined temperature to obtain a structure shown in FIG. )
Can be obtained. In the multi-layer substrate 3, the wiring of each of the substrates 1 and 2 is made of the same kind of conductive paste 14, so that when the layers are multi-layered, the bonding strength is high and the wiring connection is highly reliable.

Hereinafter, each process in the method for manufacturing a wiring board according to the present invention will be described. First, in a process of obtaining a base material by injection molding of a resin, a transfer mold (stamper) as shown in FIG. 4A is used. The transfer mold 22 has a projection 22a formed on one main surface at a portion corresponding to the wiring pattern of the wiring board. That is,
The projections 22a correspond to the grooves of the wiring board when the wiring board is molded, and the wiring pattern is formed by filling the grooves with a conductive material. The transfer mold is arranged on one side of the substrate when producing a single-sided substrate, and is disposed on both sides of the substrate when producing a double-sided substrate.

The transfer mold 22 having the protrusions 22a formed as described above is mounted on the injection mold 21 with the protrusions 22a facing inward. Thus, the mold cavity 21a is formed inside the injection mold 21 (on the side of the convex portion 22a). A resin supply port 24 is provided on a side surface of the injection molding die 21, and the supply port 24 communicates with the mold cavity 21a. Further, an injection member 23 is connected to the injection molding machine provided with the injection molding die so that the resin as the substrate raw material 25 is injected.

When the substrate raw material 25 is charged by the injection molding machine having such a configuration, the substrate raw material 25 is heated and melted, and the molten substrate raw material is supplied from the supply port 24 to the injection molding die 21.
Is injected into the mold cavity 21a. At this time, the injection mold 21 is pressurized from above with a predetermined pressure.

As described above, the injection molding is performed by the injection molding die 21 using the substrate raw material 25, thereby obtaining FIG.
A molded product 26 as shown in FIG. The molded product 26 has grooves 2 transferred to correspond to the convex portions 22a of the transfer mold.
6a are formed.

In the process of forming a through hole, FIG.
As shown in (a), the via land groove 31b of the base material 31 having the wiring groove 31a and the via land groove 31b has
As shown in FIG. 5B, a through hole 32 is formed by a drill or a laser. The periphery of the through hole 32 is formed as a via land in a circular concave shape, and has a shape on a rivet in which the via land and the via are integrated. The through hole 32
In the process shown in FIG. 4, pins may be formed on the transfer mold and formed simultaneously with the wiring grooves.

In the printing and filling process of the conductive paste,
As shown in FIG. 6A, a base material 41 having a through hole formed in a printing press base 42 is installed. At this time, the base material 41 is fixed to the printing press base 42 by vacuum chucking through a vacuum hole 42a provided in the bottom of the printing press base 42.

In this state, as shown in FIG. 6B, a conductive paste (for example, Ag paste, Cu paste,
The conductive paste 43 is filled into the wiring grooves and through holes by squeezing the g coat Cu paste (43) with a squeegee 44, which is a resin plate (FIG. 6).
(C)). Thereafter, the conductive paste 43 is dried and cured at a predetermined temperature to form wirings and connection vias (FIG. 6D). On the wiring side surface of this base material, there is a contamination layer 45 containing the remaining conductive paste and the like.

In the grinding / polishing process, if squeezing is successfully performed in the above-described process, wiring and connection vias may be formed by themselves and the wiring and connection vias may be cleaned. However, in many cases, high reliability is required. In order to ensure the above, the contamination layer 45 left on the surface as shown in FIG. 7A is removed by polishing. In addition, the variation in the thickness of the base material caused by molding the resin is reduced by about 10 μm.
In order to improve the accuracy to about m, as shown in FIG. 7B, the base material 41 is placed on a base 47, and the back surface 41b is polished with a polishing grindstone 46. Then, as shown in FIG. To
The wiring surface 41a is polished with a polishing grindstone 46. This allows
The thickness is finished in the order of 1 μm, and the width and thickness of the wiring pattern are finished with high accuracy with almost no variation.

FIGS. 8 to 10 show examples of a wiring board obtained by the method for manufacturing a wiring board according to the present invention. FIG.
Is a substrate having a double-sided pattern and having front and back connection vias, which is the simplest configuration according to the present invention. That is, in this wiring board, as shown in FIG. 8A, a through hole 53 is formed in a groove 52 formed on the surface of a base material 51 formed by injection molding of a resin, and the groove 52 and the through hole 5 are formed.
3, as shown in FIG. 8B, the conductive paste is filled with 54, and then the surface is polished. This makes it possible to provide an imposer substrate for CSP having only one-sided wiring.

FIG. 9 shows wiring and front / back connection vias 64 on both sides.
On both sides of a double-sided board 63 having a structure, a single-sided board 61 having a land and a front and back connection via 62 on one side is laminated (FIG. 9A), and integrated by hot pressing. is there. As shown in FIG. 9B, the double-sided board 65 has mounting surfaces 65a and 65b for mounting components on both sides, and has two wiring surfaces 65c and 65d inside. In this configuration, the upper and lower one boards are further laminated on the center double-sided wiring board to separate the lands for component mounting from the wiring. Is equivalent to This eliminates the need for dedicated equipment for forming the solder resist, and can be realized by equipment and technology for substrate manufacture and lamination.

FIG. 10 shows an eight-layer substrate 6 obtained by laminating and combining these basic substrates and integrally forming them by hot pressing.
6. The eight-layer board 66 is configured by a combination of a single-sided wiring + via 61 and a double-sided wiring + via 63. In this way, each basic layer unit is combined and laminated,
By performing the hot pressing, an arbitrary multilayer substrate can be obtained.

In the above-described grinding / polishing process, it is necessary to pay sufficient attention to the selection of the processing reference plane in order to prevent the uneven surface processing due to the variation in the thickness of the base material. If this selection is incorrect, uneven surface processing is performed, and the accuracy of a portion related to the wiring impedance, such as the wiring thickness and the wiring width, deteriorates. In particular, a loss occurs in a high frequency range, and a product as designed cannot be obtained.

Therefore, in the process of grinding and polishing the main surface of the base material, after flattening one main surface of the base material, the other main surface of the base material is flattened using one main surface as a reference surface. Perform processing. In this case, it is preferable that the surface having no wiring is first planarized to be a reference surface, and the surface having the wiring with respect to the reference surface is polished.

First, a pattern as shown in FIG. 11A, a wiring 72 made of a conductive paste and a via hole 73 are formed in a base material 71. Pattern formation is performed by the process described above. At this time, as shown in FIG. 11B, the thickness varies. That is, the thickness t1 in the portion A is smaller than the thickness t2 in the portion B.

At this time, as shown in FIG. 11C, the surface 73 where the wiring 72 is not formed is flattened and
Let 3 be the reference plane. When the flattening process is performed in this manner, as shown in FIG.
And the thickness t4 at the portion B becomes substantially equal. The surface 7 having the wiring with reference to the reference surface 75 obtained in this manner
4 is flattened. As a result, as shown in FIG. 11E, a wiring board having a thickness tA in the portion A and a thickness tB in the portion B substantially equal to each other is obtained.

As a result, variations in the thickness of the wiring can be suppressed, and as a result, variations in the wiring impedance can be suppressed. As a result, the characteristics particularly in the high frequency range are improved. In the flattening process, the thickness of the wiring is controlled by polishing, so that there is no instability as seen in the chemical process, and variation in characteristics between lots can be suppressed.

[0038]

As described above, in the method of manufacturing a wiring board according to the present invention, by using a method of printing a conductive paste, a large-sized facility such as a plating line or an etching line is not required, and the method is compact. It is possible to form wirings and connection vias in an environment-friendly manner with simple production equipment.

At first glance, printing a conductive paste is a disadvantageous method for forming a fine line pattern or a high-precision pattern. While a fine line pattern is possible, a substrate having a high-precision wiring pattern with almost no variation in pattern width and thickness can be realized. As a result, a high-integration substrate compatible with high-speed and high-frequency can be realized. Further, since the formation of the wiring and the formation of the connection via can be simultaneously performed by printing the conductive paste, the manufacturing cost is reduced and the manufacturing lead time is shortened.

Furthermore, it is possible to realize an arbitrary interlayer connection by appropriately combining the substrate layers having the basic structure and performing the hot pressing, and to manufacture a multilayer substrate having an arbitrary layer configuration with a short lead time. Become. In this case, when these substrate layers are laminated and hot-pressed, the connection between the substrate layers is made by bonding between the conductive pastes, and high bonding strength is obtained.

Further, since the groove shape is formed by one mold, the shape has reproducibility and there is almost no variation in pattern width due to ordinary etching. further,
A substrate having a pattern with very small variations in width and thickness can be obtained by precision polishing as a finish.

[Brief description of the drawings]

FIG. 1 is a process chart for explaining a method of manufacturing a wiring board according to an embodiment of the present invention.

FIG. 2 is a process diagram illustrating a method for manufacturing a wiring board according to an embodiment of the present invention.

FIG. 3 is a process chart for explaining a method of manufacturing a wiring board according to one embodiment of the present invention.

FIGS. 4A and 4B are views for explaining an injection molding process in a method of manufacturing a wiring board according to an embodiment of the present invention.

FIGS. 5A and 5B are views for explaining a through-hole forming process in the method for manufacturing a wiring board according to one embodiment of the present invention; FIGS.

FIGS. 6A to 6D are views for explaining a conductive paste filling process in the method of manufacturing a wiring board according to one embodiment of the present invention;

FIGS. 7A to 7C are views for explaining a grinding / polishing process in the method of manufacturing a wiring board according to one embodiment of the present invention;

FIGS. 8A and 8B are diagrams showing a wiring board obtained by a method for manufacturing a wiring board according to an embodiment of the present invention.

FIGS. 9A and 9B are diagrams showing a wiring board obtained by a method of manufacturing a wiring board according to one embodiment of the present invention.

FIG. 10 is a diagram showing a wiring board obtained by a method for manufacturing a wiring board according to one embodiment of the present invention.

FIGS. 11A to 11E are views for explaining a grinding / polishing process in the method for manufacturing a wiring board according to one embodiment of the present invention;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Single-sided board, 2 ... Double-sided board, 3 ... Multi-layer board, 11,3
1, 41: base material, 12, 26a: groove, 13: hole, 14,
43 ... conductive paste, 21 ... injection mold, 21a ...
Mold cavity, 22: transfer mold, 22a: convex part, 2
3 ... input member, 24 ... supply port, 25 ... substrate raw material, 26
... Molded product, 31a ... wiring groove, 31b ... via land groove, 32 ... through hole, 42 ... printing machine base, 42a ... vacuum hole, 44 ... squeegee, 45 ... contamination layer, 46 ... polishing whetstone, 47 ... base.

Continuation of the front page F term (reference) 5E317 AA24 BB01 BB11 CC25 CD01 CD32 GG14 GG16 5E343 AA01 AA07 AA12 BB02 BB03 BB21 BB72 DD01 EE33 EE43 ER49 GG08 GG11 5E346 AA02 AA12 AA15 AA22 CCB CC DD CC EE06 FF22 FF27 GG02 GG19 GG24 GG28 HH06 HH26 HH31

Claims (7)

[Claims] 1. A method of manufacturing a wiring board by supplying a substrate material to a mold having a cavity of a predetermined shape and molding the same, wherein a convex pattern to be transferred to a base material is formed on one main surface. Attaching the formed transfer mold to the mold main body to form a cavity on the one main surface side; and supplying a substrate material to the cavity to form a base material having a wiring groove. And a step of forming a wiring by filling the wiring groove with a conductive material. 2. The method according to claim 2, further comprising the step of forming a through hole in the base material, wherein when the conductive material is filled in the wiring groove, the wiring material is also filled in the through hole and the wiring on both surfaces of the base material is formed in the conductive material. The method for manufacturing a wiring board according to claim 1, wherein conduction is performed by using a material. 3. The method for manufacturing a wiring board according to claim 1, further comprising a step of grinding and polishing the main surface of the base material after filling the wiring groove with a conductive material. 4. The step of grinding and polishing the main surface of the base material after flattening one main surface of the base material and then using the one main surface as a reference surface and the other main surface of the base material. 4. The method for manufacturing a wiring board according to claim 3, further comprising a step of flattening the wiring board. 5. The method according to claim 4, wherein the one main surface is a surface having no wiring, and the other main surface is a surface having wiring. 6. A step of forming a cavity on the one main surface side by mounting a transfer die having a convex pattern formed on one main surface thereof to be transferred to a wiring board, on a mold main body. A wiring substrate obtained by: supplying a substrate material to the cavity to form a base material having a wiring groove; and forming a wiring by filling the wiring groove with a conductive material. 7. A multilayer board obtained by pressing a plurality of the wiring boards according to claim 6 in a stacked state.